Yoga
Yoga mats, originally uploaded by Richard-.
Recently I started doing some Yoga to help myself burn, tone up and increase my breathing on resting days. They are perfect to kill the soars inbetween days.
I am now thinking of doing them on the days of exercise as it does stretch out your body and makes it flexible.
I quite like it as it makes me concentrate and calm.
A good resource for yoga can be found here: http://yoga.about.com .